scholarly journals Addressing cluster-constant covariates in mixed effects models via likelihood-based boosting techniques

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254178
Author(s):  
Colin Griesbach ◽  
Andreas Groll ◽  
Elisabeth Bergherr
Keyword(s):  
Mixed Models ◽  
Fixed Effects ◽  
Regression Models ◽  
Computational Effort ◽  
Likelihood Inference ◽  
Gradient Boosting ◽  
Current State ◽  
Selection Step ◽  
Boosting Algorithm

Boosting techniques from the field of statistical learning have grown to be a popular tool for estimating and selecting predictor effects in various regression models and can roughly be separated in two general approaches, namely gradient boosting and likelihood-based boosting. An extensive framework has been proposed in order to fit generalized mixed models based on boosting, however for the case of cluster-constant covariates likelihood-based boosting approaches tend to mischoose variables in the selection step leading to wrong estimates. We propose an improved boosting algorithm for linear mixed models, where the random effects are properly weighted, disentangled from the fixed effects updating scheme and corrected for correlations with cluster-constant covariates in order to improve quality of estimates and in addition reduce the computational effort. The method outperforms current state-of-the-art approaches from boosting and maximum likelihood inference which is shown via simulations and various data examples.

scholarly journals Gradient boosting for linear mixed models

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Colin Griesbach ◽  
Benjamin Säfken ◽  
Elisabeth Waldmann
Keyword(s):  
Random Effects ◽  
Mixed Models ◽  
Selection Procedure ◽  
Classification Theory ◽  
Gradient Boosting ◽  
Random Structure ◽  
Boosting Algorithm ◽  
The One ◽  
Biased Estimates ◽  
Selection Of

Abstract Gradient boosting from the field of statistical learning is widely known as a powerful framework for estimation and selection of predictor effects in various regression models by adapting concepts from classification theory. Current boosting approaches also offer methods accounting for random effects and thus enable prediction of mixed models for longitudinal and clustered data. However, these approaches include several flaws resulting in unbalanced effect selection with falsely induced shrinkage and a low convergence rate on the one hand and biased estimates of the random effects on the other hand. We therefore propose a new boosting algorithm which explicitly accounts for the random structure by excluding it from the selection procedure, properly correcting the random effects estimates and in addition providing likelihood-based estimation of the random effects variance structure. The new algorithm offers an organic and unbiased fitting approach, which is shown via simulations and data examples.

scholarly journals Analysis of Prices in the Housing Market Using Mixed Models

2018 ◽  
Vol 26 (4) ◽  
pp. 102-111 ◽  
Author(s):  
Aneta Cichulska ◽  
Radosław Cellmer
Keyword(s):  
Spatial Heterogeneity ◽  
Spatial Data ◽  
Mixed Models ◽  
Fixed Effects ◽  
Regression Models ◽  
Mixed Model ◽  
Property Market ◽  
The Hierarchical Structure ◽  
Mixed Modelling ◽  
Classical Regression

Abstract Hedonic models, commonly applied for analyzing prices in the property market, do not always fulfil their role, mainly due to the application of simplified assumptions concerning the distribution of variables, the nature of relations or spatial heterogeneity. Classical regression models assumed that the variation of the explained variable (price) is explained by the effect of market features (fixed effects) and the residual component. The hierarchical structure of market data, both as regards market segments and the spatial division, suggests that statistical models of prices should also include random effects for selected subgroups of properties and interactions between variables. The mixed model provides an alternative for constructing various regression models for individual groups or for using binary variables within one model. With its appropriate structure, it makes it possible to take into account both the spatial heterogeneity and to examine the effects of individual features on prices within various property groups. It can also identify synergy effects. The article presents the issue of mixed modelling in the property market and an example of its application in a market of dwellings in Olsztyn. The research used transaction data from the price and value register, supplemented with spatial data. The obtained model was compared with classical regression models and geographically weighted regression. The study also covered the usefulness of mixed models in the mass evaluation of properties, and the possibility of using them in spatial analyses and for the development of property value maps.

scholarly journals Method for forecasting pollution of urban areas

2019 ◽  
Vol 140 ◽  
pp. 09005
Author(s):  
Anton Radaev ◽  
Elena Korneeva
Keyword(s):  
Distinctive Feature ◽  
Urban Areas ◽  
Regression Models ◽  
Environmental Indicators ◽  
Industrial Environment ◽  
Current State ◽  
State Of The Environment ◽  
Comprehensive Indicator ◽  
Linear Nature

A model for substantiating the parameters of regression models for a comprehensive indicator of environmental pollution has been developed. A distinctive feature is the separate consideration of the influence of factors of the natural and industrial environment, as well as the linear nature of the interaction of nonlinear variables. The resulting model will allow us to analyze the current state of the environment depending on the quantity and quality of environmental indicators, and also identify critical changes in it. In the urban development industry, this model will help in planning the possibility of placing objects with a high environmental burden in a particular area.

scholarly journals A Goal Scoring Probability Model for Shots Based on Synchronized Positional and Event Data in Football (Soccer)

2021 ◽  
Vol 3 ◽  
Author(s):  
Gabriel Anzer ◽  
Pascal Bauer
Keyword(s):  
Probability Model ◽  
Gradient Boosting ◽  
Event Data ◽  
Probability Score ◽  
Extreme Gradient Boosting ◽  
Boosting Algorithm

Due to the low scoring nature of football (soccer), shots are often used as a proxy to evaluate team and player performances. However, not all shots are created equally and their quality differs significantly depending on the situation. The aim of this study is to objectively quantify the quality of any given shot by introducing a so-called expected goals (xG) model. This model is validated statistically and with professional match analysts. The best performing model uses an extreme gradient boosting algorithm and is based on hand-crafted features from synchronized positional and event data of 105, 627 shots in the German Bundesliga. With a ranked probability score (RPS) of 0.197, it is more accurate than any previously published expected goals model. This approach allows us to assess team and player performances far more accurately than is possible with traditional metrics by focusing on process rather than results.

The Development of Agritourism in the Podkarpackie Voivodeship in the Light of International and National Conditions

2017 ◽  
Vol 13 ◽  
pp. 244-261
Author(s):  
Mariola Tracz ◽  
Małgorzata Bajgier-Kowalska ◽  
Radosław Uliszak
Keyword(s):  
Development Strategy ◽  
Current State ◽  
Central Statistical ◽  
Central Statistical Office ◽  
Tourism Resources ◽  
The One ◽  
The Impact ◽  
District Offices ◽  
Socio Economic Factors

Podkarpackie Voivodeship is one of the regions of Poland in which the number of agritourism entities is very high. Therefore tourism plays a significant role in its development strategy. The aim of the paper is to identify the current state of agritourism and the changes that have occurred in the region in the years 2000–2016. Specific objectives are to determine the distribution of agritourism farms and their offer, together with a comprehensive analysis of the environmental and socio-economic factors, as well as the impact of the Slovak-Ukrainian border. The report was developed on the statistical materials from the Polish Central Statistical Office, Podkarpackie Agricultural Advisory Centre in Boguchwała and data collected from municipalities and district offices that is published on their websites, as well as through interviews with 100 owners of agritourism farms in the Podkarpackie Voivodeship. The research has shown, on the one hand, the decline in the number of farms in the region and, on the other hand, the increase in the diversity of the tourist offer of these entities. Distribution of agritourism farms is closely linked to the attractiveness of natural environment and quality of secondary tourism resources. Traditional agritourism has not yet fully used its countryside, as well as cross-border advantages of its location.

PROFESSIONAL TRAINING OF ELECTRONICS ENGINEERS: APPLYING US EXPERICENCE TO UKRAINAN HIGHER EDUCATION INSTITUTIONS

2020 ◽  
pp. 80-85
Author(s):  
Olha Pavlenko
Keyword(s):  
Higher Education ◽  
Education Research ◽  
Best Practices ◽  
Cost Reduction ◽  
Professional Training ◽  
Higher Education Institutions ◽  
Academic Staff ◽  
Research And Innovation ◽  
Current State

The article discusses the current state of professional training of engineers, in particular, electronics engineers in Ukrainian higher education institutions (HEIs) and explores best practices from US HEIs. The research outlines the features of professional training of electronics engineers and recent changes in Ukrainian HEIs. Such challenges for Ukrainian HEIs as lack of collaboration between higher education and science with industry, R&D cost reduction for HEIs, and downsizing the research and academic staff, the disparity between the available quality of human capital training and the demanded are addressed. The study attempts to identify successful practices of US HEIs professional training of engineers in order to suggest potential improvements in education, research, and innovation for training electronics engineers in Ukraine.

Drug Utilization Studies – An Overview

2010 ◽  
Vol 3 (1) ◽  
pp. 803-810 ◽  
Author(s):  
Shalini S ◽  
Ravichandran V ◽  
Saraswathi R ◽  
BK Mohanty ◽  
Dhanaraj S K
Keyword(s):  
Drug Utilization ◽  
Evidence Based ◽  
Future Trends ◽  
Medical Prescription ◽  
Drug Usage ◽  
Current State ◽  
Patterns Of Use ◽  
Drug Utilization Studies ◽  
Drug Expenditures

 Aspire of the Drug Utilization Studies (DUS) is to appraise factors related to the prescribing, dispensing, administering and taking of medication, and it’s associated. Since the middle of twentieth century, interest in DUS has been escalating, first for market-only purposes, then for appraising the quality of medical prescription and comparing patterns of use of specific drugs. The scope of DUS is to evaluate the current state and future trends of drug usage, to estimate roughly disease pervasiveness, drug expenditures, aptness of prescriptions and adherence to evidence-based recommendations. The increasing magnitude of DUS as a valuable investigation resource in pharmacoepidemiology has been bridging it with other health allied areas, such as public health, rational use of drug, evidence based drug use, pharmacovigilance, pharmacoeconomics, eco-pharmacovigilance and pharmacogenetics.

Software suite for determining the tilts of tower-type structures according to terrestrial laser scanning

2020 ◽  
Vol 961 (7) ◽  
pp. 2-7
Author(s):  
A.V. Zubov ◽  
N.N. Eliseeva
Keyword(s):  
Laser Scanning ◽  
Optimization Problems ◽  
Optimization Methods ◽  
User Participation ◽  
Software Suite ◽  
Current State ◽  
Visual Basic For Applications ◽  
Operational Data ◽  
Theoretical Developments

The authors describe a software suite for determining tilt degrees of tower-type structures according to ground laser scanning indication. Defining the tilt of the pipe is carried out with a set of measured data through approximating the sections by circumferences. They are constructed using one of the simplest search engine optimization methods (evolutionary algorithm). Automatic filtering the scan of the current section from distorting data is performed by the method of assessing the quality of models constructed with that of least squares. The software was designed using Visual Basic for Applications. It contains several blocks (subprograms), with each of them performing a specific task. The developed complex enables obtaining operational data on the current state of the object with minimal user participation in the calculation process. The software suite is the result of practical implementing theoretical developments on the possibilities of using search methods at solving optimization problems in geodetic practice.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

scholarly journals Olfaction and Aging: A Review of the Current State of Research and Future Directions

i-Perception ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 204166952110203
Author(s):  
Jonas K. Olofsson ◽  
Ingrid Ekström ◽  
Maria Larsson ◽  
Steven Nordin
Keyword(s):  
Warning Signs ◽  
Future Directions ◽  
Current State ◽  
Challenging Tasks ◽  
State Of Research ◽  
To Come ◽  
Health Cognition ◽  
Olfactory Abilities ◽  
And Training

Olfaction, the sense of smell, is characterized by a notable age-dependency such that aging individuals are more likely to have poor olfactory abilities. These impairments are considered to be mostly irreversible and as having potentially profound effects on quality of life and food behavior, as well as constituting warning signs of mortality, cognitive dysfunction, and dementia. Here, we review the current state of research on aging and olfaction, focusing on five topics which we regard to be of particular relevance for the field: nutrition and health, cognition and dementia, mortality, environment and genetics, and training-based enhancement. Under each of these headlines, we provide a state-of-the-art overview and discuss gaps in our knowledge which might be filled by further research. Understanding how olfactory abilities are diminished in aging, and how they may be alleviated or recovered, involves a set of challenging tasks for researchers in the years to come.

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